Semiconductor devices using a wide-gap semiconductor such as GaN, SiC, diamond, ZnO and the like are characterized by high breakdown voltage, low resistance and a high-speed operation as compared with a semiconductor device using Si. Particularly, since a HEMT (High Electron Mobility Transistor) having an AlGaN/GaN heterostructure has high electron mobility and carrier density, high-frequency performances are favorable and ON resistance is low.
When this type of high-speed switching elements are to be actually used, high performance of a driving circuit which drives the high-speed switching element is desirable, but such a driving circuit cannot be necessarily obtained in actuality.